1. Field
Embodiments of the disclosure generally relate to a substrate support assembly for use in a plasma processing chamber, more specifically, to an electrostatic chuck having distributed heating elements to provide independent temperature control across a substrate.
2. Description of the Related Art
In the semiconductor and other industries, electrostatic chucks (ESC) are used to hold workpiece such as substrates on supports during processing of the substrate. A typical ESC may include a base, an electrically insulative layer disposed on the base, and one or more electrodes embedded in the electrically insulative layer. The ESC may be provided with an embedded electric heater, as well as be fluidly coupled to a source of heat transfer gas for controlling substrate temperature during processing. During use, the ESC is secured to the support in a process chamber. The electrode in the ESC is electrically biased with respect to a substrate disposed on the ESC by an electrical voltage source. Opposing electrostatic charges accumulate in the electrode of the ESC and on the surface of the substrate, the insulative layer precluding flow of charge therebetween. The electrostatic force resulting from the accumulation of electrostatic charge holds the substrate to the ESC during processing of the substrate.
ESCs have been developed with multiple concentric heating zones to improve processing results. The heating zones provide a means for edge to center temperature control ability to equalize reaction rates or other properties of the substrate or film because many chemical reactions performed on the workpiece, such as the etching of substrates, are highly dependent on temperature. Precisely etching a substrate within a plasma chamber can be challenging because the plasma within the chamber, pumping other chamber asymmetries may cause the temperature across the substrate to be azimuthally non-uniform. An azimuthal temperature gradient may exist asymmetrically across the substrate such that one region of the substrate is at a different temperature compared to another region of the substrate. When the temperature of the substrate is not uniform, features may not be uniformly etched into the various layers disposed on the substrate.
However, it has been difficult or prohibitively expensive for conventional ESCs to have more than a few concentric zones of temperature control across the diameter of the substrate. The inability to control substrate azimuthal temperature uniformity has an adverse effect on process uniformity both in a single substrate and between substrates.
Therefore, there is a need in the art for an improved ESC assembly that provides multiple zones of temperature control.